Variabilität des "light-harvesting-systems" im Zellzyklus von Chlorella fusca / Variability of the Light-Harvesting-System during the Cell Cycle of Chlorella fusca

The seven chlorophyll-protein complexes CPIa, CPI, LHCP₁, LHCP₂, CPa, LHCP₁ and LHCP₁₁ known in part also from the chloroplasts of higher plants were isolated from Chlorella fusca. They were characterized by their molecular weight, their absorption maxima and their ratio of chlorophyll a/chlorophyll b. The composition of the chloropyhll-protein complexes changes during the cell cycle of Chlorella fusca. The ratio of LHCP/CPI decreases at the beginning of the light period and the ratio LHCP/CPa after the 2nd hour of the light period. Both quotients increase at the 5th hour of the light period, have a maximum at the 8th hour of the light period and decrease afterwards during the second part of the cell cycle. These altera­tions are no reflections of chlorophyll-accumulation, but cause modifications in the organization of the thylakoids and influence the photosynthetic efficiency of Chlorella fusca. The size of the PSI- and PSII-units during the cell cycle was estimated by these changes of the LHCP/CPI- and LHCP/CPa-ratios. In addition evidence is given that the assembly of LHCP₁ and LHCP₂ is no simple association of the monomeric forms of LHCP_I or LHCP_II.